This invention is in the field of optical viewers or detectors such as I.sup.2 (image intensification) and IR (infrared). In particular, it is concerned with providing a device which is able to counter one of the counter-measures used against such viewers. This counter-measure is the high-power laser; such a laser can do temporary or permanent damage to a sensitive optical device (or to the human eye, for that matter). Various schemes have been made and proposed for dealing with laser counter-measures; these schemes include fast-acting electro-optical shutters, absorbing filters, and interference filters. Also, various birefringent materials are used, taking advantage of their acusto-optical or electro-optical properties. Unfortunately, all of these schemes have one disadvantage which makes them unsuitable for use as counter-counter measures against high-power lasers; although some of the schemes can theoretically block 100% of high-power laser energy in a short enough time to prevent damage to sensitive optical devices, their performances in practice fall short of 100%. Moreover, most such schemes temporarily block, on an optical device optical path, all radiation from a scene (both desired radiation and counter-measure radiation). The device is thus temporarily "blinded" during counter measures. The instant invention transmits 100% of counter-measure radiation from an optical scene while reflecting the at least part of remainder of the scene radiation to a detector. Thus, the invention allows observation of a scene during counter means; the counter-measure source (laser) will appear as a dark spot in a scene observed by a positive imaging viewer.